15:00 〜 15:15
[MZZ40-06] Apophis Kinetic Impact Test and Cratering Experiment after its Close Approach to the Earth
We define a mission concept to perform a cratering and deflection experiment at Apophis with an independent impactor spacecraft that leverages the formidable capabilities of OSIRIS-APEX as an observer. This mission concept (“ACE” for Apophis cratering experiment) is relevant to both planetary defense and science.
A 65kg spacecraft impacting Apophis at 7km/s will make a crater between 20-50m [1,2], and result in an excavation of 2-8m deep. For the estimated mass of Apophis the resulting Delta-V would be ~0.01mm/s. While incredibly small, it is ~2.5x larger than the formal 1-sigma tracking uncertainties for OSIRIS-REx at Bennu [4] and OSIRIS-APEX at Apophis would be similarly capable.
Performing this experiment after OSIRIS-APEX achieves its primary science goals means that the mass and spin state of Apophis would be known. OSIRIS-APEX will make a mass measurement to 1% accuracy [5]. Having such precise pre-impact measurements of the target will permit a very accurate measurement of the momentum transfer.
This experiment would differ from previous artificial impact experiments performed on asteroids. The DART mission impacted the satellite in a binary system (the target Dimorphos orbits Didymos), and the impact is thought to have re-shaped the target [6]. Here, we aim to impact a rubble pile asteroid and make a large crater, rather than re-shaping the target. ACE would be more energetic than HayabusaII SCI experiment that made a ~10m crater on C-type asteroid Ryugu [1].
ACE would dig deeper and expose more material than previously done on rubble piles in a scenario where the target can be studied carefully before and after [1,9,10]. The produced crater would expose deep subsurface material and allow the study of rubble pile construction and the existence, or not, of layers of fine grains.
There are many technical pathways to achieve this mission [11]. Since OSIRIS-APEX would be employed for the measurement of the target mass, imparted Delta-V and cratering outcomes, the only required vehicle is an impactor that has sufficient combination of speed and mass to produce the required 0.01mm/s Delta-V. There are several low C3 (<5 km2/s2), ballistic transfer opportunities in 2029 and 2030 that impact Apophis after the OSIRIS-APEX science campaign. The relatively low-mass and low-launch energy means the mission can use a small-to-medium lift launch vehicle, keeping costs low.
Some of the possible pathways include resonant trajectories that permit concept of operations that include a trial run, or a two-spacecraft concept with impacts on consecutive years. Similarly, other scenarios could utilize the JANUS spacecraft, where one spacecraft impacts while the other provides flyby reconnaissance of the event.
Importantly, this kinetic impact and cratering experiment would not change the risk of an Apophis impact. The experiment described was bracketed by the study of kinetic impactors changing the impact risk of Apophis [12], that found that such perturbations to Apophis’s orbit were “assuredly safe”.
References: [1] M. Arakawa, et al., Science, vol. 368, pp. 67-71, 2020. [2] E. B. Bierhaus, et al., Icarus, vol. 406, 2023. [3] Daly, R. T., et al., Icarus, vol. 384, Art. no. 115058, 2022. [4] D. Farnocchia, et al., Icarus, vol. 369, 2021. [5] D. N. DellaGiustina, et al., The Planetary Science Journal, 2023. [6] Raducan, S. D., Jutzi, M., Zhang, Y., Ormo, J., Michel, P. (2022). A&A 665. [7] Tatsumi, E. & Sugita, S. (2018) Icarus 300, 227–248. [8] Bierhaus, E. B. and 24 colleagues (2022). Nature Geoscience 15, 440–446. [9] Walsh K.J. and Ballouz R-L. et al. (2022). SciAdv 8, eabm6229. [10] Lauretta D. S. et al., (2022) Science, 377, 285-291. [11] Klein, V., Walsh K. J., and Kayser E. IAC 2024 Paper #87838. 2024. [12] J. L. Dotson, in Apophis T-6: Knowledge Opportunities for the Science of Planetary Defense, Leiden, 2023.
A 65kg spacecraft impacting Apophis at 7km/s will make a crater between 20-50m [1,2], and result in an excavation of 2-8m deep. For the estimated mass of Apophis the resulting Delta-V would be ~0.01mm/s. While incredibly small, it is ~2.5x larger than the formal 1-sigma tracking uncertainties for OSIRIS-REx at Bennu [4] and OSIRIS-APEX at Apophis would be similarly capable.
Performing this experiment after OSIRIS-APEX achieves its primary science goals means that the mass and spin state of Apophis would be known. OSIRIS-APEX will make a mass measurement to 1% accuracy [5]. Having such precise pre-impact measurements of the target will permit a very accurate measurement of the momentum transfer.
This experiment would differ from previous artificial impact experiments performed on asteroids. The DART mission impacted the satellite in a binary system (the target Dimorphos orbits Didymos), and the impact is thought to have re-shaped the target [6]. Here, we aim to impact a rubble pile asteroid and make a large crater, rather than re-shaping the target. ACE would be more energetic than HayabusaII SCI experiment that made a ~10m crater on C-type asteroid Ryugu [1].
ACE would dig deeper and expose more material than previously done on rubble piles in a scenario where the target can be studied carefully before and after [1,9,10]. The produced crater would expose deep subsurface material and allow the study of rubble pile construction and the existence, or not, of layers of fine grains.
There are many technical pathways to achieve this mission [11]. Since OSIRIS-APEX would be employed for the measurement of the target mass, imparted Delta-V and cratering outcomes, the only required vehicle is an impactor that has sufficient combination of speed and mass to produce the required 0.01mm/s Delta-V. There are several low C3 (<5 km2/s2), ballistic transfer opportunities in 2029 and 2030 that impact Apophis after the OSIRIS-APEX science campaign. The relatively low-mass and low-launch energy means the mission can use a small-to-medium lift launch vehicle, keeping costs low.
Some of the possible pathways include resonant trajectories that permit concept of operations that include a trial run, or a two-spacecraft concept with impacts on consecutive years. Similarly, other scenarios could utilize the JANUS spacecraft, where one spacecraft impacts while the other provides flyby reconnaissance of the event.
Importantly, this kinetic impact and cratering experiment would not change the risk of an Apophis impact. The experiment described was bracketed by the study of kinetic impactors changing the impact risk of Apophis [12], that found that such perturbations to Apophis’s orbit were “assuredly safe”.
References: [1] M. Arakawa, et al., Science, vol. 368, pp. 67-71, 2020. [2] E. B. Bierhaus, et al., Icarus, vol. 406, 2023. [3] Daly, R. T., et al., Icarus, vol. 384, Art. no. 115058, 2022. [4] D. Farnocchia, et al., Icarus, vol. 369, 2021. [5] D. N. DellaGiustina, et al., The Planetary Science Journal, 2023. [6] Raducan, S. D., Jutzi, M., Zhang, Y., Ormo, J., Michel, P. (2022). A&A 665. [7] Tatsumi, E. & Sugita, S. (2018) Icarus 300, 227–248. [8] Bierhaus, E. B. and 24 colleagues (2022). Nature Geoscience 15, 440–446. [9] Walsh K.J. and Ballouz R-L. et al. (2022). SciAdv 8, eabm6229. [10] Lauretta D. S. et al., (2022) Science, 377, 285-291. [11] Klein, V., Walsh K. J., and Kayser E. IAC 2024 Paper #87838. 2024. [12] J. L. Dotson, in Apophis T-6: Knowledge Opportunities for the Science of Planetary Defense, Leiden, 2023.